Hybrid and electric vehicle battery pack maintenance device

ABSTRACT

The present invention includes a battery pack maintenance device for performing maintenance on battery packs of hybrid and/or electrical vehicles (referred herein generally as electric vehicles). In various embodiments, the device includes one or more loads for connecting to a battery pack for use in discharging the battery pack, and/or charging circuitry for use in charging the battery pack. Optional input/output circuitry can be provided for communicating with circuitry of in the battery pack and/or circuitry of the vehicle.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of U.S. provisional patentapplication Ser. No. 62/620,665, filed Jan. 23, 2018, the presentapplication is also a Continuation-In-Part of U.S. Ser. No. 16/056,991,filed Aug. 7, 2018, which is a Divisional of U.S. Ser. No. 13/827,128,filed Mar. 14, 2013, which claims benefit of U.S. provisional patentapplication Ser. No. 61/665,555, filed Jun. 28, 2012, the content ofwhich is hereby incorporated by reference in its entirety.

BACKGROUND

The present invention relates to electric vehicles of the type which usebattery packs for storing electricity which is used to power thevehicle. This includes both hybrid and purely electric vehicles. Morespecifically, the present invention relates to the maintenance of suchbattery packs used in electric vehicles.

Traditionally, automotive vehicles have used internal combustion enginesas their power source. However, vehicles which are electrically poweredare finding widespread use. Such vehicle can provide increased fuelefficiency and can be operated using alternative energy sources.

Some types of electric vehicles are completely powered using electricmotors and electricity. Other types of electric vehicles include aninternal combustion engine. The internal combustion engine can be usedto generate electricity and supplement the power delivered by theelectric motor. These types of vehicles are known as “hybrid” electricvehicles.

Operation of an electric vehicle requires a power source capable ofproviding large amounts of electricity. Typically, electric vehiclesstore electricity in large battery packs which consist of a plurality ofbatteries. These batteries may be formed by a number of individualcells, or may themselves be individual cells, depending on theconfiguration of the battery and battery pack. The packs are large,replacement can be expensive and they can be difficult to access andmaintain.

Another requirement may be to discharge the battery down to a fixedstate of charge, say 30%, for safe transport. It is desired to performthis work as quickly as possible and as safely as possible. Further,since this work often occurs outside and away from permanent structures,light weight portability and operation from batteries is required. Theselarge batteries may have a fully charged voltage in the 400 VDC range,and can store as much as 100 KWh. Further, since this is an activity isinfrequently performed, an inexpensive solution is desired.

SUMMARY

The present invention includes a battery pack maintenance device forperforming maintenance on battery packs of hybrid and/or electricalvehicles (referred herein generally as electric vehicles). In variousembodiments, the device includes one or more loads for connecting to abattery pack for use in discharging the battery pack, and/or chargingcircuitry for use in charging the battery pack. Optional input/outputcircuitry can be provided for communicating with circuitry of in thebattery pack and/or circuitry of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram of a battery maintenance device inaccordance with the present invention coupled to an electric vehicle.

FIG. 2 is a more detailed block diagram of the battery maintenancedevice of FIG. 1.

FIG. 3 is an electrical schematic diagram of a controllable load for usein the battery maintenance device of FIG. 2.

FIG. 4 is a diagram which illustrates one example arrangement ofcomponents within the battery maintenance device to promote cooling ofsuch components.

FIG. 5 is a diagram of a plug having an additional load resistance.

FIG. 6 is a perspective view of a housing having resistive loading coilsin accordance with one embodiment.

FIG. 7 is a schematic diagram of a controllable resistance load.

FIG. 8 is a graph showing power, discharge current and temperatureduring battery discharge.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Maintenance of automotive vehicles with internal combustion engines is awell-known art. Procedures are known for servicing the internalcombustion engine of the vehicles, the drive train, the battery (whichis generally used to start the vehicle and operate the electricaldevices within the vehicle), and the fuel storage and distributionsystem. In contrast, widespread use of electrical vehicles is arelatively new phenomenon and there is an ongoing need for improvedprocedures for performing maintenance on the batteries of such vehicles.For example, when a traditional vehicle with an internal combustionengine is involved in an accident, it is typical to drain the gasolineor other fuel from the vehicle for safety purposes. In contrast, when anelectrical vehicle is involved in an accident, the battery pack of thevehicle may contain a relatively large amount of energy, and may even bein a fully charged state. It is not at all apparent how the battery packcan be discharged as there are many different types of battery pack, aswell as various techniques used to access the packs. Further, after anaccident, systems of the vehicle may not be functioning properly and mayprevent maintenance from being performed on the battery pack whereby thebattery pack cannot be discharged using normal procedures. In oneaspect, the present invention provides an apparatus and method forsafely accessing the battery pack of an electrical vehicle anddischarges the battery pack. However, the present invention is notlimited to this configuration and may be used generally to performmaintenance on the battery pack of an electric vehicle.

The device of the present invention can be used to “de-power” thebattery pack of an electric vehicle or provide other maintenance on thebattery pack including charging the battery pack. In general, thisactivity can be problematic for a number of reasons. First, differenttypes of electric vehicles use different types of battery packs. Theconfiguration, voltages, and connection to such packs vary greatly.Further, the vehicle itself typically includes “intelligence” to controlthe charging and discharging, as well as monitoring the status of thebattery pack. Further still, some battery packs themselves include“intelligence” to control the charging and discharging of the batterypack as well as monitor the status of the battery pack. The device ofthe present invention is capable of interfacing with a databus of thevehicle and/or a databus of the battery pack in order to control andmonitor operation of the battery pack. Again, the connection to thesedatabuses varies greatly between vehicles. Further still, the dataformat and specific data varies between vehicles. The problem ofperforming maintenance on a battery pack is exacerbated when a vehiclehas been in an accident. The battery pack may be physically difficult toaccess and it may be difficult to obtain electrical connections to thebattery pack and/or vehicle for discharging the battery as well as forcommunicating over the vehicle or battery pack databus. Depending on thedamage which occurs during an accident, the battery pack may be isolatedfor safety reasons. This isolation presents another challenge inaccessing the battery pack. Further, the circuitry of the maintenancedevice must be capable of operating with the relatively high DCvoltages, for example 400 Volts, which are present in electrical vehiclebattery packs. These high voltages must be isolated from the logic andcontrol circuitry of the device as well as the operator. Additionally,in one aspect, the device also includes a charger function for use incharging some or all of the cells of a battery pack in order to placethe battery pack into service.

Electric vehicles typically includes “contactors” which are electricallyoperated relays (switches) used to selectively couple the high voltagefrom the battery pack to the powerful electric motors used in the drivetrain of the vehicle. In order to access the battery pack from alocation on the vehicle, it is necessary for these contactors to beclosed to complete the electrical circuit. However, in an accident, thecontrolling electronics of the vehicle and/or battery pack willtypically disconnect (open) the contactors for safety purposes in orderto isolate the battery pack from the vehicle. Thus, in one embodiment,the present invention communicates with the controller of the electricalvehicle or battery pack, or directly with the contactors, to cause thecontactors to close and thereby provide access to the high voltage ofthe battery pack. When communicating with the control system of thevehicle, the device of the present invention can provide information tothe vehicle system indicating that it is appropriate for the contactorsto close. Thus, failure indications or other errors, including errorsassociated with a vehicle being in an accident, must be suppressed.Instead, information is provided to the vehicle system by the batterypack maintenance device which indicates that it is appropriate for thecontactors to be closed.

FIG. 1 is a simplified block diagram showing battery pack maintenancedevice 100 coupled to an electric vehicle 102. The vehicle 102 isillustrated in a simple block diagram and includes a battery pack 104used to power the vehicle 102 including providing power to motor(s) 106of the vehicle. The vehicle 102 includes a vehicle controller 108coupled to a databus 110 of the vehicle. The controller 108 receivesinformation regarding operation of the vehicle through sensors 112 andcontrols operation of the vehicle through outputs 114. Further, thebattery pack 104 is illustrated as including its own optional controller120 which monitors operation of the battery pack 104 using battery packsensors 122.

During operation, the electric vehicle 102 is controlled by thecontroller 108, for example, based upon input from a driver throughoperator I/O 109. Operator I/O 109 can comprise, for example, a footaccelerator input, a brake input, an input indicating an position of asteering wheel, information related to a desired gearing ratio for adrive train, outputs related to operation of the vehicle such as speed,charging information, amount of energy which remains in the battery pack104, diagnostic information, etc. The controller 108 can controloperation of the electric motors 106 to propel the vehicle, as well asmonitor and control other systems of the vehicle 102. The controller 120of battery pack 104 can be used to monitor the operation of the batterypack 104. For example, the sensors 122 may include temperature sensorsconfigured to disconnect the batteries of the battery pack if athreshold temperature is exceeded. Other example sensors include currentor voltage sensors, which can be used to monitor charge of the batterypack 104. FIG. 1 also illustrates contactor relays 130 of the vehicle102 which are used to selectively decouple the battery pack 104 fromsystems of the vehicle 102 as discussed above. For example, thecontroller 108 can provide a signal to cause the contactors 130 to closethereby connecting the battery pack 104 to electrical systems of thevehicle 102.

Battery pack maintenance device 100 includes a main unit 150 whichcouples to the vehicle through a low voltage junction box 152 and a highvoltage junction box 154. These junction boxes 152, 154 are optional andother techniques may be used for coupling the maintenance device 100 tothe vehicle 102. Maintenance device 100 includes a microprocessor 160,I/O circuitry 162 and memory 164 which contains, for example,programming instructions for use by microprocessor 160. The I/Ocircuitry 162 can be used to both user input, output, remote input,output as well as input and output with vehicle 102. The maintenancedevice 100 includes a controllable load 170 for use in discharging thebattery pack 104. An optional charging source 171 is also provided andcan be used in situations in which it is desirable to charge the batterypack 104, for example, to perform maintenance on the battery pack 104.The high voltage junction box 154 is used to provide an electricalconnection between terminals of the battery pack 104 and the maintenancedevice main unit 150. Using this connection, batteries within thebattery pack 104 can be discharged using the load 170 or charged usingthe charging source 171. Similarly, low voltage junction box 152 is usedby battery pack maintenance device 100 to couple to low voltage systemsof the electric vehicle 102. Such systems include the databus 110 of thevehicle, sensors 112, outputs 114, etc. Through this connection, asdiscussed above, the maintenance device 100 can gather informationregarding the condition of systems within the vehicle 102 including thebattery pack 104, and can control operation of systems within thevehicle 102. Similarly, through this connection, the outputs fromsensors 112 can be changed or altered whereby altered sensor outputs canbe provided to controller 108. This can be used, for example, to causecontroller 108 to receive information indicating that the vehicle 102 orbattery pack 104 is in a condition which is different than from what thesensors 112 are actually sensing. For example, this connection can beused to cause the contactors 130 to close to thereby provide anelectrical connection to the battery pack 104. Further, the low voltagejunction box 152 can be used to couple to the controller 120 and/orsensors 122 of the battery pack 104. The junction boxes 152, 154 coupleto vehicle 102 through the use of an appropriate connector. Theparticular connector which is used can be selected based upon thespecific type of vehicle 102 and the type of connections which areavailable to an operator. For example, OBD II connection can be used tocouple to the databus 110 of the vehicle. Other plugs or adapters may beused to couple to sensors 112 or outputs 114. A particularly style plugmay be available for coupling the high voltage junction box 154 to thebattery pack 104. If there are no contactors which are available or ifthey cannot be accessed or are unresponsive, in one configuration clipsor other types of clamp on or selectively connectable contactors can beused to perform the coupling.

FIG. 2 is a simplified block diagram of a battery pack maintenancedevice 100 in accordance with one example embodiment of the presentinvention. The device includes microprocessor 160 which operates inaccordance with instructions stored in a memory 164. A power supply isused to provide power to the device. The power supply 180 can be coupledto an AC power source, such as a wall outlet or other high power source,for use in charging the battery pack 104 of the vehicle 102.Additionally, the power supply 180 can be coupled to a DC power source,such as a 12 Volt battery, if the device 100 is only used fordischarging of the vehicle battery pack 104. For example, in addition tothe battery pack 104, many electric vehicles also include a standard 12Volt automotive battery. This 12 Volt automotive battery can be used topower maintenance device 100. The microprocessor communicates with anoperator using an operator input/output 182. Other input/outputcircuitry 184 is provided for use in physically connecting to a datacommunication link such as an RS232, USB connection, Ethernet, etc. Anoptional wireless I/O circuit 186 is also provided for use incommunicating in accordance with wireless technologies such as WiFitechniques, Bluetooth®, Zigbee®, etc. Low voltage input/output circuitry190 is provided for use in communicating with the databus of the vehicle108, the databus of the battery pack 104, or receiving other inputs orproviding outputs to the vehicle 102. Examples include the CANcommunication protocol, OBDII, etc. Additionally, contact closures orother voltage inputs or outputs can be applied to the vehicle using thelow voltage I/O circuitry 190. FIG. 2 also illustrates an operator shutoff switch 192 which can be activated to immediately disconnect the highvoltage control 170 from the battery 104 using disconnect switch 194.Other circuit configurations can be used to implement this shut offcapability. This configuration allows an operator to perform anemergency shut off or otherwise immediately disconnect the device 100from the battery if desired.

The low voltage junction box 152 also provides an optional power output.This power can be used, for example, to power components of the vehicle102 if the vehicle 102 has lost power. This can be useful, for example,to provide power to the controller 108 of the vehicle 102 such thatinformation may be gathered from the vehicle and various components ofthe vehicle can be controlled such as the contactors 130.

In one configuration, the connection between the high voltage controlcircuitry 170 and the high voltage junction box 154 is through Kelvintype connectors. This can be used to eliminate the voltage drop whichoccurs when large currents are drawn through wiring thereby provide moreaccurate voltage measurements. The actual connection between thejunction box 154 and the battery pack 104 need not be through a Kelvinconnection if the distance between the junction box 154 and the batterypack 104 is sufficiently short for the voltage drop across theconnection leads to be negligible. Isolation circuitry such as fuses maybe provided in the junction box 154 to prevent the application of a highvoltage or current to the maintenance device 100 and thereby protectcircuitry in the device. Similarly, the low voltage junction box 152and/or the low voltage I/O 190 may include isolation circuitry such asoptical isolators, inductors to provide inductive coupling, or othertechniques. The low voltage junction box 152 may also include anoptional user output and/or input 196. For example, this may be adisplay which can be observed by an operator. An example displayincludes an LED display, or individual LEDs, which provides anindication to the operator regarding the functioning of the low voltagejunction box, the vehicle, or the battery pack. This can be used tovisually inform an operator regarding the various functions beingperformed by the low voltage junction box, voltages detected by the lowvoltage junction box. A visual output and/or input 198 can be providedon the high voltage junction box 154.

The appropriate high voltage junction box 154 and low voltage junctionbox 152 can be selected based upon the particular vehicle 102 or batterypack 104 being inspected. Similarly, the junction boxes 152, 154 can beselected based upon the types of connections which are available in aparticular situation. For example, if the vehicle his damaged, it may beimpossible to couple to the battery pack 104 through availableconnectors. Instead, a junction box 154 can be employed which includesconnection probes which can be coupled directly to the battery pack 104.Further still, if such a connection is not available or is damaged,connectors can be provided for coupling to individual cells or batterieswithin the battery pack 104.

The use of the low voltage and high voltage junction boxes 152, 154 areadvantageous for a number of reasons. The junction boxes can be used toprovide a standardized connection to the circuitry of the maintenancedevice 100. From a junction box 152, 154, specialized connectors can beprovided for use with different types of vehicles and/or battery packs.Similarly, different types of junction boxes 152, 154 can be utilizedfor different vehicles and/or battery packs. The junction boxes 152, 154allow a single set cable connection to extend between the device 100 anda remote location. This provides better cable management, ease of use,and increased accuracy.

In addition to use as a load for discharging the battery, the highvoltage control circuitry may also optionally include a charging for usein charging the battery.

FIG. 3 is a schematic diagram of controllable load 170. In FIG. 3, anumber of isolated gate bipolar transistors (IGBT) 220A, 220B, 220C, and220D are shown and controlled by a gate connection to microprocessor160. The IGBTs 220A-D connect to load resistors 222A, 222B, 224A, and224B. As illustrated in FIG. 3, the four load resistors are 33 OHMresistors. Using the transistors 220A-D, the resistors 222A, B and 224A,B can be coupled in various series-parallel configurations in order toapply different loads to the battery pack 104. In this way, the loadapplied to the battery pack 104 is controllable by microprocessor 160.In one aspect, the present invention includes isolated gate bipolartransistors (IGBT) to selectively couple loads to the battery pack 104for discharging the pack. An IGBT is a transistor configured with foursemiconducting layers arranged as PNPN. A metal oxide semiconductor isarranged to provide a gate. The configuration provides a transistorwhich is controlled easily in a manner similar to a field effecttransistor but which is also capable of switching large currents like abipolar transistor.

When the device 100 is coupled to a vehicle 102 which has been in anaccident, the device can perform various tests on the vehicle 102 todetermine the condition of the vehicle and the battery. For example, inone aspect, the device 100 detects a leakage between the positive andnegative terminals of the battery pack 102 and the ground or chassis ofthe vehicle 102. For example, a wheat stone bridge circuit 230 can beused between the positive and negative terminals of the battery pack 104with one of the legs of the bridge connected to ground.

During discharging of the vehicle battery pack 104, data can becollected from the battery pack. For example, battery packs typicallyinclude sensors 122 such as voltage, current and temperature sensorsarranged to collect data from various locations within the battery pack.This information can be obtained by the maintenance device 100 via thecoupling to the databus 110. During discharge, any abnormal parametersmeasured by the sensors can be used to control the discharge. Forexample, if the battery pack 104 is experiencing excessive heating, thedischarge rate can be reduced until the battery temperature returns toan acceptable level. If any of the internal temperature sensors of thebattery pack are not functioning, an external battery pack temperaturesensor can be used to detect the temperature of the battery pack.Similarly, if cells within the pack are experiencing an abnormally highcurrent discharge, the discharge rate can be reduced. Further still, ifsuch data cannot be obtained because the sensors are damages or thedatabus is damaged or inaccessible, the maintenance device 100 canautomatically enter a slow/safe discharge state to ensure that thebattery is not damaged.

When placing a battery pack 104 into service, the maintenance device 100can identify individual cells or batteries within the pack 104 which aremore or less charged than other cells. Thus, the individual cells orbatteries within a pack can be balanced whereby they all havesubstantially the same charge capacity and/or state of charge as theother cells or batteries within the pack.

In another aspect of the present invention, the maintenance device 100is capable of providing a “jump start” to a hybrid electric vehicle 102.For example, if the internal combustion engine of a hybrid electricvehicle is started using power directly from the battery pack and if thecharge of the battery pack 104 is too low, there is insufficient energyavailable to start the engine. The maintenance device 100 of the presentinvention can be used to provide sufficient power to a starter motor ofthe internal combustion engine for starting the engine. Once theinternal combustion engine is running, the engine itself is used tocharge the battery pack 104.

In FIG. 3, a voltage sensor 232 is connected across the wheat stonebridge 230. Further, the bridge is optionally connected to electricalground through switch 234. Any voltage detected by voltage sensor 232across the bridge 230 is an indication that there is a current leakbetween the positive and/or negative terminals of the battery pack 104and the electrical ground or chassis of the vehicle 102. The voltagesensor 232 can provide an output to microprocessor 130 and used to alertan operator of a potentially dangerous situation and indicate that thebattery pack 104 must be disconnected from the vehicle 102 beforefurther maintenance is performed.

FIG. 3 also illustrates a relay 226 which is used to isolate the loadresistances 222/224 from the battery pack until a discharge is commandedby the microprocessor 160. The voltage across the battery pack 104 canbe measured using a voltage sensor 242 connected in series with aresistance 240. The output from sensor 242 is provided to microprocessor160 for use in performing maintenance in the battery pack 104.

During operation, the components of the device 100 may experience agreat deal of heating. An air flow cooling system can be used todissipate the heat. FIG. 4 shows one such configuration. As illustratedin FIG. 4, the air flow moves from the low power electronics 300, passedthe high power electronics 302 and over the load resistors 222A, B and224A, B. The air flow then leaves the housing of the device 100. In FIG.4, the air flow is controlled by fans 304. The fans 304 can becontrolled using microprocessor 160 whereby their speed can be adjustedas needed based upon measurements from temperature sensors 306 which canbe placed at various locations within the housing of device 100. In thisconfiguration, hot air generated by the load resistance is immediatelyblown out of the housing rather than past any components.

Some electrical vehicles include what is referred to as a “pre-chargecontactor.” The pre-charge contactor can be used to charge capacitancesof the vehicle at a slow and controlled rate prior to switching in themain contactor 130 shown in FIG. 1. This prevents excessive currentdischarge from the battery pack when the main contactor is activated andthe pack is directly coupled to the loads of the vehicle including thetraction module of the vehicle which is used to control electric motorsof the vehicle.

In another aspect, some or all of the information obtained duringtesting and discharge of a battery pack 104 is retrieved and stored, forexample in the memory 164 shown in FIG. 1, for subsequent access. Thisinformation can be offloaded to another device, for example a USB driveor the like, or transmitted over a network connection. This can beparticularly useful to examine information retrieved after a vehicle hasexperienced an accident. The information can be information which isdownloaded from the controller 108 of the vehicle 102 and may also beinformation related to how the vehicle battery pack 104 was dischargedand removed of service.

In another aspect, more than one maintenance device 100 can be coupledto a battery pack 104 and the multiple devices can be configured to workin tandem. More specifically, the devices 100 can be coupled using theinput/output circuitry 184 shown in FIG. 2 whereby one of the devices100 operates as a master and one or more other devices 100 operate asslaves under the control of the master device. This arrangement can beused to increase the rate at which a battery pack 104 is discharged. Insuch a configuration, a bridgeable power supply may also be employed.

FIG. 5 is a simplified diagram showing a removable plug 350 which can beselectively coupled to battery pack maintenance device 100. Removableplug 350 includes a 5 OHM resistor 352 configured to connect in parallelthrough connectors 354 and 356. Removable plug 350 includes a magnet 360configured to actuate a reed switch 362. Reed switch 362 connects tomicroprocessor 160 whereby microprocessor 160 can sense the presence ofthe plug 350. When plug 350 is coupled to device 100, the resistance ofone or more of the 33 OHM resistors 222A,B and 224 A,B can be changedbecause the resistor is in series with the 5 OHM resistor yielding aresistance of about 4.3 OHMs. However, any configuration desired can beprovided. This allows the device 100 to apply a smaller resistance tothe battery pack 104 thereby increasing the discharge rate if desired.For example, a particular battery pack may be of a sufficiently lowvoltage to allow for an increased current draw to thereby increase therate at which the battery pack 104 is discharged. Using reed switch 362,the microprocessor 160 is able to detect the presence of the plug 350whereby calculations which rely on the value of applied load resistancecan be compensated appropriately. Although only a single resistor 352 isshown, the plug 350 may include any number of resistors to be placed inparallel with load resistances in the device 100. Preferably plug 350includes a cooling mechanism to reduce the heating of resistor 352. Forexample, the plug 350 may include metal or other heat conducting fins orthe like. A fan may also be employed. The fan may be the same coolingfan used in device 100 or, plug 350 may optionally include its own fan.In another embodiment, the alternative resistance values are locatedwithin the main unit, and are switched into circuit using the removableplug.

FIG. 6 is a perspective view of another example embodiment of acontrollable load 170 illustrated in a housing 402. In the configurationof FIG. 6, resistive elements are provided using a number of resistivecoils 400. In one example embodiment, these resistive coils can be thetype of coils used in consumer applications such as electric clothingdryers. For example, one such coil is rated at approximately 5.3 KW at240 volts. Note that if the rated voltage is exceeded, the coil willmelt and become an open circuit. Further, it is also preferable that thecoils 400 have resistances which are similar. The coils 400 are carriedon supports 404 preferably made of an electric insulator capable ofhandling high temperatures. To assist in heat dissipation, an air flowcan be provided across the coils 400 as shown in FIG. 4.

FIG. 7 is a simplified schematic diagram of another example embodimentof controllable load 100. In the configuration of FIG. 7, the four coils400 illustrated in FIG. 6 are electrically connected in aseries/parallel configuration. In this configuration, switches K1, K2,K3 and K4 are provided for controlling the resistance provided bycontrollable load 100. These switches can be any type of switchincluding relays or transistor switches. In one configuration, theswitches are manual switches. Switches K1 and K2 control two parallellegs of the circuit while switches K3 and K4 control the amount ofresistance in series in each leg. In this configuration, a maximumdischarge capability of 20 KW is provided if both switches K1 and K2 areclosed and switches K3 and K4 are open. The B+ and B− connections areused for coupling to the storage battery and fusible links 406 areprovided for safety. In one example configuration, if the voltage acrossterminals B+ and B− drops below 240 volts DC, switch K3 and/or switch K4can then be closed to reduce the resistance applied to battery 104 andoptimize the loading of the battery. FIG. 8 is a graph showing theloading performance of such an arrangement. As illustrated in FIG. 8,the step change occurs when the resistive load provided by controllableload 100 is decreased, for example, by activating switch K2

As mentioned above, the fans illustrated in FIG. 4 can be used toprovide an air flow across the coils 400. In one configuration, all ofthe fans control circuits and relays may be operated by 12 volt DC andcan be powered, for example, by an auxiliary battery or a “cigarettelighter” output from a vehicle such as a tow truck. A double insulationtechnique can be used proximate the load coils such that any electricalfault, for example a heater coil failure, cannot be conducted to alocation outside of the housing 402. Optional temperature safety sensors306 shown in FIG. 4 can be used. The temperature sensors 306 can beprovided on both the inlet and the outlet of each heater coil and can beused to detect fan failure or blocked air flow. This configuration canalso be used to detect the amount that the air is heated by the coil. Inanother example configuration, fusible links 404 may provide hard wiredtemperature cutout switches to prevent overheating. In such aconfiguration, when a temperature threshold is reached, the switch willopen. Data obtained during discharge can be logged to a memory such asmemory 164 such as a local flash drive or other local storage device. Inanother configuration, the logged data is sent to a remote location suchas cloud storage for analysis. Such records can be of significance forwarranty or insurance purposes.

In one configuration, the voltage sensor 232 is used to detect leakagecurrents in the battery undergoing discharge. The device can alsomonitor battery cell voltages and temperatures to ensure that unsafeconditions are not being created during discharge.

The input/output circuitry 190 can be used to connect to a databus ofthe vehicle, for example, through an OBDII connection in order tocollect information such as VIN, software and hardware version numbers,etc. The device can communicate with the battery ECU (Electronic ControlUnit) using any appropriate protocol including CAN, LIN, or others, inorder to obtain specific battery information and discharge protocols.The device can be connected as a slave unit to another piece of shopequipment either using a hardwire connection or a wireless connectionsuch as Bluetooth or Wi-Fi. Reverse polarity protection as well asovervoltage protection can be provided. Other safety techniques forelectrical potential, temperature and axis points can be fullyinterlocked to prevent operation of the unit. In one configuration, theinput/output 184 can include a barcode scanner which can then be used tocapture specific information such as battery type or serial number aswell as vehicle identification number, etc. In another exampleconfiguration, input/output circuitry 184 can include a remotetemperature sensor that can be electrically coupled to the discharger toreport battery temperature. This is useful when internal batterytemperature sensors are damaged or inoperative. The devices are scalablesuch that multiple controllable loads 100 can be connected in parallel.Relay contacts can also be provided and available externally to controlvarious circuits on the battery pack undergoing discharge. Additionalvoltage sensing connections such as those provided by junction box 152can be used to monitor various circuits on the battery pack.

Another example configuration includes a high voltage DC to DC convertersuch as power supply 180 shown in FIG. 2. In such a configuration, thehigh voltage output from the battery pack can be converted to a lower DCvoltage for use in powering the device.

As discussed above, in some configurations the present invention can bearranged to measure a dynamic parameter of the battery pack. In such aconfiguration, a forcing function is applied to the battery pack and adynamic parameter such as dynamic conductance, resistance, admittance,etc. can be determined based upon a change in the voltage across thebattery pack and the current flowing through the battery pack. Theforcing function can be any type of function which has a time varyingaspect including an AC signal or a transient signal.

In one aspect, the maintenance device can be configured to “balance”individual cells within the battery pack. The balancing can be performedby selected cells or individual batteries within the pack which havesimilar storage capacity and state of charge. The charging feature ofthe device can be used to increase the charge of a cell or battery tothat of other cells or batteries. Similarly, the maintenance device canbe used to discharge individual cells or batteries to a level similar tothat of other cells or batteries within the pack.

In another aspect, the device of FIG. 1 includes an ambient temperaturesensor. The microprocessor can use information from the ambienttemperature sensor in determining how the battery pack should bedischarged. For example, if the ambient temperature is high, thedischarge rate can be reduced.

During discharge of the battery pack, the discharge profile can bemonitored to ensure proper operation. For example, if the voltage of thebattery suddenly drops, this can be an indication that a componentwithin the battery has failed or a short circuit has occurred.

Different types of junction boxes and connection cables can be usedbased upon the particular type of vehicle and battery pack undermaintenance. The microprocessor can provide information to the operatorprompting the operator to use the appropriate junction box or cable.This can be based upon the operator inputting the vehicle identificationnumber (VIN) to the microprocessor, or other identifying informationincluding an identification number associated with the battery pack.During discharging of the battery pack, the microprocessor can alsoprovide information to the operator which indicates the time remainingto complete the discharge. The microprocessor 160 can also detect if thecorrect junction box and cable have been coupled to the device and tothe battery pack for the particular battery pack and vehicle undermaintenance. Information can be provided to the operator if the wrongcabling or junction box has been employed.

The device of the present invention can be used with battery packs whichhave been removed from a vehicle as well as individual batteries, orgroups of batteries, within a pack. For example, a battery packtypically includes a battery connector assembly which is used by thevehicle 102 to couple to the battery pack 104. However, when the batterypack 104 is removed from the vehicle 102, the device 100 can directlycouple to this battery connector assembly and thereby charge ordischarge the battery pack, perform tests on the battery pack, interactwith devices on the battery pack including sensors, controllers, etc. Asdiscussed above, the device 100 can include multiple connectors for usein connecting the low voltage junction box 152 and/or the high voltagejunction box 154 to the vehicle 102 and/or battery pack 104. This allowsthe device 100 to easily be modified to interact with different types ofbatteries or vehicles by simply selecting the appropriate connector. Inone configuration, the connectors include some type of identifier whichcan be read by the device 100 whereby the microprocessor 160 and device100 can receive information to thereby identify the type of connector inuse. This allows the microprocessor 100 to know what types ofinformation or tests may be available through the various connectors. Inanother example, the operator uses operator I/O 182 shown in FIG. 2 toinput information to the microprocessor 160 related to the type ofconnector(s) being used. In another example embodiment, themicroprocessor 160 may receive information which identifies the type ofvehicle or battery on which maintenance is being performed. Thisinformation can be input by an operator using the operator I/O 182, orthrough some other means such as by communicating with the databus ofthe vehicle, scanning a barcode or other type of input, etc. Based uponthis information, the microprocessor can provide an output to theoperator using operator I/O 182 which informs the operator which type ofinterconnect cable should be used to couple the low voltage junction box152 and/or the high voltage junction box 154 to the vehicle and/orbattery pack.

The operator I/O 182 may include a display along with a keypad input ortouchscreen. The input may take various formats, for example, a menudriven format in which an operator moves through a series of menusselecting various options and configurations. Similarly, the operatorI/O 182 can be used by the microprocessor 160 to step the operatorthrough a maintenance procedure. In one configuration, the memory 164 isconfigured to receive a user identification which identifies theoperator using the equipment. This can be input, for example, throughoperator I/O 182 and allows information related to the maintenance beingperformed to be associated with information which identifies aparticular operator. Additional information that can be associated withthe maintenance data include tests performed on the vehicle and/orbattery, logging information, steps performed in accordance with themaintenance, date and time information, geographical locationinformation, environmental information including temperature, testconditions, etc., along with any other desired information. Thisinformation can be stored in memory 164 for concurrent or subsequenttransmission to another device or location for further analysis. Memory164 can also store program instructions, battery parameters, vehicleparameters, testing or maintenance information or procedures, as well asother information. These programming instructions can be updated, forexample, using I/O 184 or 186, through an USB flash drive, SD card orother memory device, or through some other means as desired. This allowsthe device 100 to be modified, for example, if new types of vehicles orbattery pack configurations are released, if new testing or maintenanceprocedures are desired, etc.

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No. 16/056,991, filed Aug. 7, 2018, entitled HYBRID ANDELECTRIC VEHICLE BATTERY PACK MAINTENANCE DEVICE, all of which areincorporated herein by reference in their entireties.

What is claimed is:
 1. A maintenance device for coupling to a battery ofan electric vehicle and performing maintenance on the battery,comprising: a device housing; a controller in the housing configured tocontrol operation of the maintenance device; a plurality of wire loadingcoils configured to apply a discharge load to the battery; and loadcontrol circuitry configured to selectively couple at least two of theplurality of wire loading coils to the battery in response to an outputfrom the controller.
 2. The apparatus of claim 1 including a junctionbox configured to couple the controllable load to the battery pack. 3.The apparatus of claim 1 including communication circuitry configured tocouple to a databus of the electric vehicle.
 4. The apparatus of claim 1including communication circuitry configured to couple to a battery packof the electric vehicle.
 5. The apparatus of claim 1 including powersupply circuitry configured to be powered by a 12 volt source.
 6. Theapparatus of claim 1 including a shut off switch configured to beactuated by an operator.
 7. The apparatus of claim 1 including aninsulated gate bipolar transistor coupled to the load.
 8. The apparatusof claim 1 including a junction box configured to couple the controllerto a databus of the vehicle.
 9. The apparatus of claim 1 including abridge circuit configured to couple to the battery pack and wherein avoltage difference across the bridge circuit is indicative of electricalcurrent leakage from the battery pack to electrical ground.
 10. Theapparatus of claim 1 wherein the controller is configured to communicatewith a databus of the electric vehicle during discharge of the batterypack.
 11. A slave device configured to couple to the apparatus of claim1 the slave device including a slave controllable load configured toapply a slave load to the battery pack.
 12. The apparatus of claim 11wherein the controller controls the slave controllable load to therebyapply a total load which is lesser than the controllable load.
 13. Theapparatus of claim 1 wherein the controller is electrically isolatedfrom the load.
 14. The apparatus of claim 1 including a memoryconfigured to log information related to discharging of the batterypack.
 15. The apparatus of claim 1 further including charge circuitryconfigured to electrically charge a cell or battery of the battery pack.16. The apparatus of claim 1 wherein the load includes at least two loadresistances configured to the selectively electrically coupled to thebattery pack.